1. Field of the Invention
The present invention relates to the paper/pulp industry and more particularly relates to an improved method and apparatus for the removal of fibrous material from a paper/pulp process water stream wherein both undesirable waste material and desirable fibrous paper/pulp material can be removed from a flow stream associated with the paper/pulp process water system. Even more particularly, the present invention relates to an improved method and apparatus for recovering fibrous material from a paper/pulp process water stream wherein the process water stream is distributed over a primary treatment vessel and an overflow weir exits the vessel with separation and the weir removing fibrous material therefrom on a continuous basis.
2. General Background
In the process of manufacturing pulp and/or paper, water is used extensively to wash, bleach, screen, clean, transport, or form the final fiber product. Contaminants can enter this water stream in many different ways depending upon the particular process involved. Contaminants can be thus either organic or inorganic in nature and are considered to be contaminants based solely upon their desirability in the final product.
In order to remove contaminants from the process stream, a portion of the water is constantly bled from the system for treatment prior to reuse and/or prior to discharge from the facility. Unfortunately, because of the nature of the process involved, a significant amount of desirable fiber can be carried along with the discharge. In order to comply with the Clean Water Act of 1971, most paper/pulp manufacturing facilities use primary treatment to remove the contaminants from the water stream prior to discharge from the facility. In such primary treatment, typically a settling basin or a clarifier is used to allow the majority of contaminants and the fibrous material to settle together according to Stokes Law. This settled material is then removed and disposed of. At some facilities, this settled material which includes both contaminants and the fibrous material may be returned to the process stream if the final product specification allows. However, the reuse of the fibrous material which is mixed with the contaminants is very rare.
It would thus be desirable to classify and separate the desirable fibrous material from the majority of the other contaminants, allowing for productive use of this recovered fiber and a general reduction in the amount of solid waste material that must be disposed of from the facility.